Last year, stand-up comic David Baddiel allowed a TV crew to film his dad Colin who has a rare form of dementia. The resulting documentary The Trouble with Dad was shown on Channel 4 this week, revealing the complicated truth about Frontotemporal dementia (also known as Pick’s disease).

For anyone who doesn’t know much about dementia, The Trouble with Dad could have been rather troubling. For a start, the people who appear in the documentary (and who live with dementia) don’t seem to have particularly bad memories and still recognise their families. They aren’t all elderly either – one of them is only in her forties. Their behaviour may be rude, bizarre or eccentric but that doesn’t mean they have dementia…does it?

Well yes it does. For as anyone with personal experience can testify, dementia doesn’t only cause memory problems (sometimes memory issues don’t become apparent until the condition is quite advanced) and it doesn’t only affect the elderly either. The Trouble with Dad shines a light on a rare form of dementia called Frontotemporal dementia or Picks disease, the main symptoms of which include personality and behaviour changes. For Ken, who appears in the documentary, it can means bursting into song whenever the mood takes him, which can be a little waring on his family, but is otherwise rather endearing. For others, it can mean losing the power of speech completely, which for their families is heart breaking.

But the main focus of this poignant and sensitive documentary is on Colin Baddiel, 82, the father of David, Ivor and Dan. Colin has a mouth like a sewer (Warning: do not watch this documentary if you are easily offended by bad language) and although he is now housebound and receiving 24 hour care, he still manages to verbally abuse his sons whenever the mood takes him. His continuous use of obscenities is, of course, partly down to his dementia but also, according to David, simply part of his father’s personality, which could explain why it’s quite funny as well as quite sad.

The Baddiel boys unflinching honesty about Colin, and their relationship with him, is what makes this documentary so compelling, it’s full of love and hope, though at times it is painful to watch. Like any family living with dementia, Colin’s sons continually search for ways to connect with their dad, and make the most of the time they have left, whether it’s a trip in a Rolls Royce (a birthday treat) or a pint in the pub, their efforts are admirable. David’s delight when Colin remembers the punch line to one of his favourite jokes (a rude one, naturally) is testament to his love and affection for this complicated, funny, dysfunctional and difficult dad…who also happens to have dementia. Their relationship is not perhaps the sort of relationship most sons would have with their parents, but having already lost his mother, David know that it’s better than nothing. ‘It’s still him,’ he says. ‘It’s still my dad.’

David Baddiel was aware that allowing his father to be filmed in this way might cause controversy. After all, Colin wasn’t able to give his consent in the way a person without dementia might. However, he felt it was a risk worth taking. After all, how else are we to see and understand the troubling and often disturbing reality of dementia if we aren’t allowed to see it up close? And judging by the positive response The Trouble with Dad has already received from viewers who’ve described it as ‘sensitive, brave, funny and positive,’ we think he might have been right.

Watch it on catch up http://www.channel4.com/programmes/the-trouble-with-dad and tell us what you think